Mineral by-products have been used in stabilizing semi-solid, odorous organic waste through bulk drying, odor absorption, and granulation (see e.g., U.S. Pat. Nos. 3,877,920 and 4,554,002). In addition, mineral materials including sand, diatomaceous earth, perlite, and various mineral reagent powders have been used in conjunction with fluidized heating, drying and burning of sludges and oily waste (see e.g., U.S. Pat. Nos. 4,159,682, 4,787,323, 4,970,803, 5,490,907). However, existing thermal dryers have ongoing problems with drying waste high in organics, particularly sewage sludges, in the waste sticking to dryer surfaces, charring and producing burnt organic matter odors, and catching on fire.
Organic waste has traditionally been disposed of by incineration, primarily in stand-alone plants designed for a particular waste. Wet waste, such as dewatered sewage sludge filter cake, requires supplemental fuel to initiate and sustain burning, and sludges are not self-burning until solids contents are greater than about 30%. Dry organic waste such as paper and cardboard are net energy producers and municipal refuse incinerators that use these feedstocks are capable of significant power generation. Likewise, dried animal manures like broiler chicken litter, which contains sawdust that is used as bedding, can have a solids content in excess of 75% and can be incinerated with out supplemental fuel. Processes of more efficiently disposing of organic waste are desirable.
NOx created during the burning of coal can react with volatile organic compounds in the presence of heat and sunlight to form ozone. Gaseous ammonia, in the form of commercial anhydrous ammonia and its main derivative, urea, are currently used in treating fossil fuel combustion exhausts for NOx removal. This is a very expensive process, however. Therefore, inexpensive sources of ammonia or methods of recycling ammonia are desirable.